Experimental study about the diffraction of high-density grating in deep Fresnel field

The experimental study about the diffraction of high-density grating in deep Fresnel region is performed in this paper. A microscope-magnification method is advanced, and the diffraction intensity distributions of high-density grating in deep Fresnel region are measured. The quasi-Talbot image of grating is also obtained in experiment. The corresponding theoretic results are also provided for convenient comparison with the experimental ones. The coincidence of experimental and theoretical results verifies the reliability of microscope-magnification method. This method can be used in the measurement of the diffraction of sub-wavelength structure in near field and deep Fresnel region.